Compounds derived from diaminopyrazole substituted by a heteroaromatic radical and their use in oxidation dyeing of keratinous fibers

ABSTRACT

The invention concerns compounds derived from diaminopyrazole of formula (I), wherein: Ar is a 5- or 6-membered heteroaromatic radical capable of being condensed with one or several heteroaromatic cycles each comprising 5 or 6 members, and their physiologically acceptable addition salts with and acid. The invention also concerns compositions containing such a compound for oxidation dyeing of keratinous fibers and the method using said compositions

This application is a U.S. national phase application under 35 U.S.C. §371 of International Application No. PCT/FR02/02397 filed 9 Jul. 2002,which claims priority to French Application No. 01/09622 filed 18 Jul.2001, the entire disclosures of which are incorporated herein byreference.

The present invention relates to novel compounds derived fromdiaminopyrazole, to a composition for the oxidation dyeing of keratinfibers, and in particular of human keratin fibers such as the hair,comprising at least one compound derived from diaminopyrazole asoxidation base, and to the oxidation dyeing processes using it.

It is known practice to dye keratin fibers, and in particular humanhair, with dye compositions containing oxidation dye precursors, inparticular ortho- or para-phenylenediamines, ortho-aminophenols orpara-aminophenols and heterocyclic compounds such as diaminopyrazolederivatives, which are generally referred to as oxidation bases. Theoxidation dye precursors, or oxidation bases, are colorless or weaklycolored compounds which, when combined with oxidizing products, can giverise to colored compounds and dyes by a process of oxidativecondensation.

It is also known that the shades obtained with these oxidation bases canbe varied by combining them with couplers or coloration modifiers, thelatter being chosen in particular from aromatic meta-diamines,meta-aminophenols, meta-diphenols and certain heterocyclic compounds.

The variety of molecules used as oxidation bases and couplers makes itpossible to obtain a wide range of colors.

The so-called “permanent” coloration obtained by means of theseoxidation dyes must moreover satisfy a certain number of requirements.Thus, it must have no toxicological drawbacks and it must allow shadesof the desired strength to be obtained and have good resistance toexternal agents (light, bad weather, washing, permanent-waving,perspiration and friction).

The dyes must also allow white hairs to be covered, and, lastly, theymust be as unselective as possible, i.e. they must allow the smallestpossible differences in coloration to be produced over the entire lengthof the same keratin fiber, which may indeed be differently sensitized(i.e. damaged) between its tip and its root. They must also show goodchemical stability in the formulations, and must have a goodtoxicological profile.

Furthermore, for a certain number of applications, dyes that producechromatic shades on the hair are desired.

Patent application EP 375 977 discloses 4,5-diaminopyrazole derivativesof use as coloring agents in oxidation dyeing.

Application DE 197 30 412 also discloses compounds of azabispyrazoletype which can be used as direct dyes in the range of the reds.

However, these dyes do not satisfy all the above requirements.

The Applicant has now discovered, entirely surprisingly andunexpectedly, that it is possible to obtain dyes, which are capable ofproducing powerful, particularly chromatic, bright and relativelyunselective colorations, which have excellent properties of resistanceto the various attacking factors to which keratin fibers may besubjected, by using as oxidation base the diaminopyrazoles of theformula (I) below or physiologically acceptable salts thereof.

One subject of the present invention is thus a compound derived fromdiaminopyrazole of formula (I):

in which Ar is a 5- or 6-membered heteroaromatic radical which can becondensed with one or more aromatic or heteroaromatic rings, eachcomprising 5 or 6 ring members.

Another subject of the invention is a compound of formula (I),characterized in that Ar is optionally substituted by at least oneradical chosen from linear or branched C₁ to C₆ alkyl radicals, linearor branched C₁ to C₆ alkoxy radicals, linear or branched C₁ to C₆ mono-or polyaminoalkyl radicals, linear or branched C₁ to C₆ mono- orpolyhydroxyalkyl radicals, amino, hydroxyl, F, Cl, Br, I,trifluoromethyl, CHO, CO₂H, CO₂Me, CO₂Et, CONH₂, CONHR₁, CON(R₁)₂, SO₃H,SO₂NH₂, SO₂Me or piperazinyl radicals, or phenyl radicals optionallysubstituted by at least one radical chosen from linear or branched C₁ toC₆ alkyl radicals, linear or branched C₁ to C₆ alkoxy radicals, linearor branched C₁ to C₆ mono- or polyaminoalkyl radicals, linear orbranched C₁ to C₆ mono- or polyhydroxyalkyl radicals or amino, hydroxyl,F, Cl, Br, I, trifluoromethyl, CHO, CO₂H, CO₂Me, CO₂Et, CONH₂, SO₃H,SO₂NH₂, SO₂N(R₁)₂ or SO₂Me radicals,

R₁ being chosen from linear or branched C₁ to C₆ alkyl radicals, linearor branched C₁ to C₆ mono- or polyaminoalkyl radicals, linear orbranched C₁ to C₆ mono- or polyhydroxyalkyl radicals, ortrifluoromethyl, CHO, CO₂Me, CO₂Et, CONH₂, SO₃H, SO₂NH₂ or SO₂Meradicals, and physiologically acceptable salts thereof.

Preferably, R₁ will be chosen from C₁ to C₄ alkyl derivatives.

The term “5- or 6-membered heteroaromatic” is understood to mean, withinthe meaning of the present application, an aromatic nucleus formed of 5or 6 atoms, at least one of which is a heteroatom chosen from the groupformed by N, O and S.

It will preferably be a radical chosen from the pyridinyl, pyrazinyl,pyrimidinyl, pyridazinyl, pyrrolyl, imidazolyl, pyrazolyl, furanyl,thiophenyl, triazolyl or triazinyl radicals. More preferably still, itwill be a pyridinyl radical.

The term “radical condensed with one or more aromatic or heteroaromaticrings, each comprising 5 or 6 ring members” is understood to mean,within the meaning of the present application, a radical comprising 2 or3 aromatic or heteroaromatic rings such that at least two carbon atomsof said radical are common to at least 2 of said aromatic orheterocyclic rings.

It will preferably be a radical chosen from the naphthyl, azanaphthyl,diazanaphthyl, triazanaphthyl or tetraazanaphthyl radicals, such as thequinolinyl, isoquinolinyl, oxyisoquinolinyl, quinoxalinyl ornaphthyridinyl radicals; or the acridinyl, pyrazolo-[3,4-b]pyridinyl,pyrazolo[3,4-c]pyridazinyl or thieno-[3,2-c]pyridinyl radicals.

A subject of the invention is also the physiologically acceptable acidsalts of the compounds of formula (I), such as the hydrochlorides,hydrobromides, sulfates, tartrates, lactates or acetates.

A subject of the invention is also a composition for the oxidationdyeing of keratin fibers, and in particular of human keratin fibers suchas the hair, characterized in that it contains, in a medium that issuitable for dyeing, as oxidation base, at least one diaminopyrazole offormula (I) above, or physiologically acceptable acid salts thereof.

As mentioned above, the colorations obtained with the oxidation dyecomposition in accordance with the invention are powerful, particularlybright and chromatic. They in particular produce red shades that arefree of or contain very little blue or yellow. Furthermore, they showexcellent properties of resistance with respect to the action of variousexternal agents (light, bad weather, washing, permanent-waving,perspiration and friction).

A subject of the invention is also a process for the oxidation dyeing ofkeratin fibers using such a dye composition.

As examples of diaminopyrazoles of formula (I) according to theinvention, mention may be made of the compounds belonging to thefollowing classes:

1) Pyridine Series

Structure Name Structure Name Structure Name

2-Pyridin-2-yl-2Hpyrazole-3,4-diamine

2-Isoquinolin-1-yl-2H-pyrazole-3,4-diamine

2-(6-Methyl-4-trifluoro-methyl-pyridin-2-yl)-2H-pyrazole-3,4-diamine

2-(6-Chloro-4-trifluoro-methyl-pyridin-2-yl)-2Hpyrazole-3,4-diamine

2-(5-Chloro-3,6-bistrifluoro-methyl-1-pyridin-2-yl)-2Hpyrazole-3,4-diamine

2-(1,3,4-Trimethyl-1H-pyrazolo-[3,4-b]pyridin-6-yl)-2H-pyrazole-3,4-diamine

2-(3-Amino-pyridin-2-yl)-2H-pyrazole-3,4-diamine

2-(5-Amino-pyridin-2-yl)-2H-pyrazole-3,4-diamine

2-(5,7-Bistrifluoromethyl[1,8]naphthyridin-2-yl)-2H-pyrazole-3,diamine

2-(2-Oxy-isoquino-lin-3-yl)-2H-pyrazole-3,4-diamine

2-(3-Amino-4-methyl-1H-pyrzolo[3,4-b]pyridin-6-yl)-2H-pyrazole-3,4-diamine

2-(6-Fluoro-pyridin-2-yl)2H-pyrazole-3,4-4-diamine

2-(4,6-Bis-trifluoromethyl-pyridin-2-yl)-2H-pyrazole-3,4-diamine

2-(6-Chloro-pyridin-2-yl)-2H-pyrazole-1,4-diamine

2-(4,5-Bis-trifluoromethyl-pyridin-2-yl-(2H-pyrazole-3,4-diamine

2-(5-Trifluoromethyl-pyridin-2-yl)-2H-pyrazole-3,4-diamine

2-(3-Trifluoromethyl-pyridin-2-yl)-2H-pyrazole-3,4-diamine

2-(4,5-Diamino-pyrazol-1-yl)-pyridine-3,5-diamine

2-(3-Amino-5-trifluoromethylpyridin-2-yl)-2H-pyrazole-3,4-diamine

2-(3-Trifluoromethyl-pyridin-2-yl)-2H-pyrazole-3,4-diamine

2-(4-Amino-3,5-difluoro-pyridin-2-yl)-2H-3,4-diamine

2-(4-Amino-3,5,6-trifluoro-pyridin-2-yl)-2H-pyrazole-3,4-diamine

2-Thieno[3,2-C]pyridin-4-yl-2H-pyrazole-3,4-diamine

2-Pyridin-3-yl-2H-pyrazole-3,4-diamine

2-Pyridin-4-yl-2H-pyrazole-3,4-diamine

2-(7-Chloro-quinolin-4-yl)-2H-pyrazole-3,4-diamine

2-Acridin-9-yl-2H-pyrazole-3,4-diamine

2-(3,5-Dichloro-pyridin-4-yl)-2H-pyrazole-3,4-diamine

3,5,6-Trichloro-4-(4,5-diamino-pyrazol-1yl)-pyridine-2-carboxylicacid

2-(2-Bromo-pyridin-4-yl)-2H-pyrazole-3,4-diamine

2-Quinolin-4-yl-2H-pyrazole-3,4-diamine

2-(7-Methyl-quinolin-4-yl)-2H-pyrazole-3,4-diamine

2-(8-Trifluoromethyl-quinolin-4-yl)-2H-pyrazole-3,4-diamine

2-(7-Amino-quinolin-4-yl)-2H-pyrazole-3,4-diamine

2-(7-Fluoro-quinolin-4-yl)-2H-pyrazole-3,4diamine

2-(7-BVromo-quinolin-4-yl)-2H-pyrazole-3,4-diamine

2-(7-Methoxy-quinolin-4-yl)-2H-pyrazole-3,4-diamine

2-(7-Ethyl-quinolin-4-yl)-2H-pyrazole-3,4-diamine

2-(7-Methyl-quinolin-4-yl)-2H-pyrazole-3,4-diamine

2-(2-6-Dimethyl-quinolin-4-yl)-2H-pyrazole-3,4-diamine

2-(8-Isopropyl-2-methyl-quinolin-4-yl)-2H-pyrazole-3,4-diamine

2-(2,6,8-Trimethyl-quinolin-4-yl)-2H-pyrazole-3,4-diamine

2-(5-Chloro-8-methoxy-2-methyl-quinolin-4-yl)-2H-pyraxole-3,4-diamine

2-(3-methyanesulfonyl-pyridin-4-yl)-2H-pyrazole-3,4-diamine2) Pyrazine Series

Structure Name Structure Name Structure Name

2-Pyrazin-2-yl-2H-pyrazole-3,4-diamine

2-Quinoxalin-2-yl-2H-pyrazole-3,4-diamine

2-(3,7-Dichloro-quinoxalin-2-yl)-2H-pyrazole-3,4-diamine

2-(5-Chloro-3,6-diphenyl-pyrazin-2-yl)-2Hpyrazole-3,4-diamine

2-(3-Trifluoromethylquinoxalin-2-yl)-2H-pyrazole-3,4-diamine3) Pyrazole Series

Structure Name

2′H-[1,3′]Bipyr-azolyl-4,5-diamine

4,5-Diamino-5′-methyl-2′H-[1,3′]bipyra-zolyl-4′-carboxylicacidethylester

2′,5′-Dimethyl-2′H-[1,3′]bipyrazol-yl-4,5,4′-triamine

1′H-[1,4′]Bipyrazo-lyl-4,5-diamine

2-(4,5-Diphenyl-1H-pyrazolo[3,4-c]pyridazin-3-yl)-2H-pyrazole-3,4-diamine4) Pyrimidine Series

Structure Name Structure Name Structure Name

2-Pyrimidin-4-yl-2H-pyrazole-3,4-diamine

2-(2-Amino-pyrimidin-4-yl)-2H-pyrazole-3,4-diamine

2-(2,6-Dichloro-pyrimindin-4-yl)-2H-pyrazole-3,4-diamine

2-Pyrimidin-5-yl-2H-pyrazole-3,4-diamine

2-(2,4,6-Trichloro-pyrimidin-5-yl)-2H-pyrazole-3,4-diamine

2-(2-Piperazin-1-yl-pyrimidin-5-yl)-2H-pyrazole-3,4-diamine5) Furan Series:

Structure Name Structure Name Structure Name

2-Furan-2-yl-2H-pyrazole-3,4-diamine

5-(4,5-Diamino-pyrazol-1-yl)-furan-2-carbaldehyde

2-(4-Bromo-furan-2-yl)-2H-pyrazole-3,4-diamine

2-(4-Phenyl-furan-2-yl)-2H-pyrazole-3,4-diamine

5-[(4,5-Diamino-pyrazol-1-yl)-furan-2-yl]-methanol

5-(4,5-Diamino-pyrazol-1-yl)furan-3-carboxylicacid

3-(4,5-Diamino-pyraxol-1-yl)furan

5-(4,5-Diamino-pyrazol-1-yl)-5Hfuran-2-one6) Thiophene Series:

Structure Name Structure Name Structure Name

2-Thiophen2-yl-2H-pyrazole-3,4-diamine

5-(4,5-Diaminopyrazol-1-yl)-thiophene-2-carbaldehyde

2-(4-Bromo-thiophen-2-yl)-2H-pyrazole-3,4-diamine

2-(4-Isopropylthiophen2-yl-2H-pyrazole-3,4-diamine

2-(5-Aminoethyl-thiophen-2-yl)-2H-pyrazole-3,4-diamine

5-(4,5-Diaminopyrazol-1-yl)-thiophene-3-carboxylic acid

2-Thiophen2-yl-2H-pyrazole-3,4-diamine

[5-(4,5-Diaminopyrazol-1-yl)-thiophen-3-yl]methanol7) Triazole Series:

Structure Name Structure Name Structure Name

2-(3H-[1,2,3]Triazol-4-yl)-2H-pyrazole-3,4-diamine

2-(2H-[1,2,3]Triazol-3-yl)-2H-pyrazole-3,4-diamine

2-(2-Phenyl-2H-[1,2,3]triazol-3-yl)-2H-pyrazole-3,4-diamine8) Triazine Series:

Structure Name Structure Name Structure Name

2-[1,3,5]Triazin-2-yl-2H-pyrazole-3,4 diamine

2-(4,6-Dichloro-[1,3,5]triazin-2-yl)-2H-pyrazole-3,4 diamine

2-(4,6-Difluoro-[1,3,5]triazin-2-yl)-2H-pyrazole-3,4 diamine9) Pyrrole, Imidazole and Pyridazine Series

Structure Name Structure Name Structure Name

2-(1H-Pyrrol-3-yl)-2H-pyrazole-3,4-diamine

2-(1H-Pyrrol-2-yl)-2H-pyrazole-3,4-diamine

2-(1H-Imidazol-2-yl)-2H-pyrazole-3,4-diamine

2-(1H-Pyrrol-4-yl)-2H-pyrazole-3,4-diamine

2-Pyridazin-3-yl)-2H-pyrazole-3,4-diamine

2-Pyridazin-4-yl)-2H-pyrazole-3,4-diamine

The diaminopyrazoles of formula (I) that are preferred according to theinvention have the following structures:

Structure Name Structure Name Structure Name

2-Pyridin-2-yl-2H-pyrazole-3,4-diamine

2-Isoquinolin-1-yl-2H-pyrazole-3,4-diamine

2-Thieno[3,2-c]pyridin-4-yl-2H-pyrazole-3,4 diamine

2-Pyridin-3-yl-2H-pyrazole-3,4-diamine

2-Quinolin-4-yl-2H-pyrazole-3,4-diamine

2-Pyrazin-2-yl-2H-pyrazole-3,4-diamine

2-Quinoxalin-2-yl-2H-pyrazole-3,4-diamine

2′H-[1,3′]Bipyrazolyl-4,5-diamine

1′H-[1,4′]Bipyrazolyl-4,5-diamine

2-Pyrimidin-4-yl-2H-pyrazole-3,4-diamine

2-Pyrimidin-5-yl-2H-pyrazole-3,4-diamine

2-Puran-2-yl-2H-pyrazole-3,4-diamine

2-(4-Bromo-furan-2-yl)-2H-pyrazole-3,4-diamine

3-(4,5-Diamino-pyraxol-1-yl)-furan

5-(4,5-Diamino-pyraxol-1-yl)-furan-3-carboxylic acid

3-(4,5-Diamino-pyraxol-1-yl)-5H-furan-2-one

2-Thiophen-2-yl-2H-pyrazole-3,4-diamine

2-Thiophen-3-yl-2H-pyrazole-3,4-diamine

2-3H-[1,2,3]Triazol-4-yl)-2H-pyrazole-3,4-diamine

2-2H-[1,2,4]Triazol-3-yl)-2H-pyrazole-3,4-diamine

2-[1,3,5]Triazin-2-yl)-2H-pyrazole-3,4-diamine

2-(1H-Pyrrol-3-yl)-2H-pyrazole-3,4-diamine

2-(1H-Pyrrol-2-yl)-2H-pyrazole-3,4-diamine

2-(1H-Imidazol-2-yl)-2H-pyrazole-3,4-diamine

2-(1H-Imidizol-4-yl)-2H-pyrazole-3,4-diamine

2-Pyridazin-3-yl-2H-pyrazole-3,4-diamine

2-Pyridazin-2-yl-2H-pyrazole-3,4-diamine

The diaminopyrazoles of formula (I) that are more particularly preferredaccording to the invention are 2-pyridin-2-yl-2H-pyrazole-3,4-diamine,2-pyridin-3-yl-2H-pyrazole-3,4-diamine,2-pyridin-4-yl-2H-pyrazole-3,4-diamine,2-pyrazin-2-yl-2H-pyrazole-3,4-diamine,2′H-[1,3′]bipyrazolyl-4,5-diamine, 1′H-[1,4′]bipyrazolyl-4,5-diamine,2-pyrimidin-4-yl-2H-pyrazole-3,4-diamine,2-pyrimidin-5-yl-2H-pyrazole-3,4-diamine,2-furan-2-yl-2H-pyrazole-3,4-diamine, 3-(4,5-diaminopyrazol-1-yl)furan,2-thiophen-2-yl-2H-pyrazole-3,4-diamine,2-thiophen-2-yl-2H-pyrazole-3,4-diamine,2-(3H-[1,2,3]triazol-4-yl)-2H-pyrazole-3,4-diamine,2-(2H-[1,2,4]triazol-3-yl)-2H-pyrazole-3,4-diamine,2-[1,3,5]triazin-2-yl-2H-pyrazole-3,4-diamine,2-(1H-pyrrol-3-yl)-2H-pyrazole-3,4-diamine,2-(1H-pyrrol-2-yl)-2H-pyrazole-3,4-diamine or the addition salts thereofwith physiologically acceptable acids.

The diaminopyrazoles of formula (I) according to the invention areprepared, for example, according to the following general preparationmethod:

Synthetic Scheme:

The operating conditions used will depend on the radical Ar of thereactant chosen.

The dye composition according to the invention especially contains from0.001% to 10% by weight, preferably from 0.05% to 6% by weight and evenmore preferably from 0.1% to 3% by weight of at least onediaminopyrazole of formula (I) or of the salts thereof.

The dye composition in accordance with the invention may also contain,in addition to the diaminopyrazole(s) defined above, at least oneadditional oxidation base that may be chosen from the oxidation basesconventionally used in oxidation dyeing and among which mention may bemade especially of para-phenylenediamines, bis(phenyl)alkylenediamines,para-aminophenols, ortho-aminophenols and heterocyclic bases other thanthe diaminopyrazoles used in accordance with the invention.

Among the para-phenylenediamines that may be mentioned moreparticularly, for example, are para-phenylenediamine,para-tolylenediamine, 2,6-dimethyl-para-phenylenediamine,2-β-hydroxyethyl-para-phenylenediamine,2-n-propyl-para-phenylenediamine, 2-isopropyl-para-phenylenediamine,N-(β-hydroxypropyl)-para-phenylenediamine,N,N-bis(β-hydroxyethyl)-para-phenylenediamine,4-amino-N-(β-methoxyethyl)aniline and the para-phenylenediaminesdescribed in French patent application FR 2 630 438, and the additionsalts thereof.

Among the bis(phenylalkylenediamines that may be mentioned moreparticularly, for example, areN,N′-bis-(β-hydroxyethyl)-N,N′-bis(4′-aminophenyl)-1,3-diaminopropanol,N,N′-bis(β-hydroxyethyl)-N,N′-bis(4′-aminophenyl)ethylenediamine,N,N′-bis(4-aminophenyl)tetramethylenediamine,N,N′-bis(β-hydroxyethyl)-N,N′-bis(4-aminophenyl)tetramethylenediamine,N,N′-bis-(4-methylaminophenyl)tetramethylenediamine andN,N′-bis(ethyl)-N,N′-bis(4′-amino-3′-methylphenyl)ethylenediamine, andthe addition salts thereof.

Among the para-aminophenols that may be mentioned more particularly, forexample, are para-aminophenol, 4-amino-3-methylphenol,4-amino-3-fluorophenol, 4-amino-3-hydroxymethylphenol,4-amino-2-methylphenol, 4-amino-2-hydroxymethylphenol,4-amino-2-methoxymethylphenol, 4-amino-2-aminomethylphenol and4-amino-2-(β-hydroxyethylaminomethyl)phenol, and the addition saltsthereof.

Among the ortho-aminophenols that may be mentioned more particularly,for example, are 2-aminophenol, 2-amino-5-methylphenol,2-amino-6-methylphenol and 5-acetamido-2-aminophenol, and the additionsalts thereof.

Among the heterocyclic bases that may be mentioned more particularly,for example, are pyridine derivatives, pyrimidine derivatives, pyrazolederivatives other than the diaminopyrazoles of formula (I) used inaccordance with the invention, and the addition salts thereof.

When they are used, these additional oxidation bases preferablyrepresent from 0.0005% to 12% by weight relative to the total weight ofthe dye composition and even more preferably from 0.005% to 6% by weightrelative this weight.

The oxidation dye compositions in accordance with the invention may alsocontain at least one coupler and/or at least one direct dye, especiallyto modify the shades or to enrich them with glints.

The couplers that may be used in the oxidation dye compositions inaccordance with the invention may be chosen from the couplersconventionally used in oxidation dyeing, and among which mention may bemade especially of meta-phenylenediamines, meta-aminophenols,meta-diphenols, mono- or polyhydroxylated naphthalene derivatives andheterocyclic couplers such as, for example, indole or pyridinederivatives, and the addition salts thereof with an acid.

These couplers are chosen more particularly from 2-methyl-5-aminophenol,5-N-(β-hydroxyethyl)amino-2-methylphenol,6-chloro-2-methyl-5-aminophenol, 3-aminophenol, 1,3-dihydroxybenzene,1,3-dihydroxy-2-methylbenzene, 4-chloro-1,3-dihydroxybenzene,2,4-diamino-1-(β-hydroxyethyloxy)benzene,2-amino-4-(β-hydroxyethylamino)-1-methoxybenzene, 1,3-diaminobenzene,1,3-bis(2,4-diaminophenoxy)propane, 3-ureido-aniline,3-ureido-1-dimethylaminobenzene, sesamol,1-β-hydroxyethylamino-3,4-methylenedioxybenzene, α-naphthol,2-methyl-1-naphthol, 6-hydroxyindole, 4-hydroxyindole,4-hydroxy-N-methylindole, 2-amino-3-hydroxypyridine,6-hydroxybenzomorpholine, 3,5-diamino-2,6-dimethoxypyridine,1-N-(β-hydroxyethyl)amino-3,4-methylenedioxybenzene and2,6-bis-(β-hydroxyethylamino)toluene, and the addition salts thereof.

When they are present, these couplers especially represent from 0.0001%to 10% of the total weight of the dye composition, preferably from0.005% to 5% by weight and even more preferably from 0.1% to 3% of thisweight.

In general, the addition salts with an acid that may be used in thecontext of the dye compositions of the invention (oxidation bases andcouplers) are chosen especially from the hydrochlorides, hydrobromides,sulfates, tartrates, lactates and acetates.

The medium that is suitable for dyeing (or support) used according tothe invention consists of water or of a mixture of water and at leastone organic solvent chosen from C₁–C₄ lower alkanols, polyols and polyolethers, aromatic alcohols, similar products and mixtures thereof.

The dye composition according to the invention may also contain variousadjuvants conventionally used in compositions for dyeing the hair, suchas anionic, cationic, nonionic, amphoteric or zwitterionic surfactantsor mixtures thereof, anionic, cationic, nonionic, amphoteric orzwitterionic polymers or mixtures thereof, mineral or organicthickeners, antioxidants, reducing agents, sunscreens, penetratingagents, sequestering agents, fragrances, buffers, dispersants,conditioners, for instance silicones, film-forming agents, preservingagents and opacifiers.

The pH of the dye composition according to the invention is between 3and 12.

Needless to say, a person skilled in the art will take care to selectthis or these optional additional compound(s) such that the advantageousproperties intrinsically associated with the oxidation dye compositionin accordance with the invention are not, or are not substantially,adversely affected by the envisaged addition(s).

The dye composition according to the invention may be in various forms,such as in the form of liquids, creams or gels, or in any other formthat is suitable for dyeing keratin fibers, and especially human hair.

Another subject of the invention is a process for dyeing keratin fibers,and in particular human keratin fibers such as the hair, using the dyecomposition as defined above.

According to this process, at least one dye composition as defined aboveis applied to the fibers, for a time that is sufficient to develop thedesired coloration, either in air or using an oxidizing agent. The dyecomposition may optionally contain oxidation catalysts, so as toaccelerate the oxidation process.

According to a first embodiment of the process of the invention, thecoloration of the fibers may be performed without adding an oxidizingagent, solely by contact with atmospheric oxygen.

According to a second embodiment of the process of the invention, atleast one dye composition as defined above is applied to the fibers, thecolor being revealed at acidic, neutral or alkaline pH using anoxidizing agent that is added to the composition just at the time ofuse, or which is present in an oxidizing composition appliedsimultaneously or sequentially in a separate manner.

According to this second embodiment of the dyeing process of theinvention, the dye composition described above is preferably mixed, atthe time of use, with an oxidizing composition containing, in a mediumthat is suitable for dyeing, at least one oxidizing agent present in anamount that is sufficient to develop a coloration. The mixture obtainedis than applied to the keratin fibers and is left for an action time of3 to 50 minutes and preferably 5 to 30 minutes, after which the fibersare rinsed, washed with shampoo, rinsed again and dried.

The oxidizing agent present in the oxidizing composition as definedabove may be chosen from the oxidizing agents conventionally used forthe oxidation dyeing of keratin fibers, and among which mention may bemade of hydrogen peroxide, urea peroxide, alkali metal bromates andpersalts such as perborates and persulfates. Hydrogen peroxide isparticularly preferred.

The pH of the oxidizing composition containing the oxidizing agent asdefined above is such that, after mixing with the dye composition, thepH of the resulting composition applied to the keratin fibers preferablyranges between 3 and 12, and even more preferably between 5 and 11. Itis adjusted to the desired value by means of acidifying or basifyingagents usually used in the dyeing of keratin fibers, and as definedabove.

The oxidizing composition as defined above may also contain variousadjuvants conventionally used in compositions for dyeing the hair and asdefined above.

The composition that is finally applied to the keratin fibers may be invarious forms, such as in the form of liquids, creams or gels, or in anyother form that is suitable for dyeing keratin fibers, and especiallyhuman hair.

Another subject of the invention is a multi-compartment device or dyeing“kit” or any other multi-compartment packaging system, a firstcompartment of which contains the dye composition as defined above, anda second compartment of which contains the oxidizing composition asdefined above. These devices may be equipped with a means for applyingthe desired mixture to the hair, such as the devices described in patentFR-2 586 913 in the name of the Applicant.

The examples that follow are intended to illustrate the inventionwithout, however, limiting its scope.

EXAMPLES Example of the synthesis of2-pyridin-2-yl-2H-pyrazole-3,4-diamine hydrochloride

Synthesis of 2-pyridin-2-yl-2H-pyrazol-3-ylamine (1):

A solution of 2-hydrazinopyridine (38.9 g, 453 mmol) was slowly added toa solution of 3-ethoxyacrylonitrile (31.5 g, 324 mmol) in pentanol (155ml). The reaction mixture was brought to reflux for 5 h.2-Hydrazinopyridine (10.6 g, 97 mmol) was again added and the reactionwas allowed to continue to reflux for 4 h. The progress of the reactionis observed by TLC and, when the reaction is complete, the mixture isconcentrated under reduced pressure until the excess hydrazinopyridinehas precipitated. The filtrate was purified by column chromatography togive 2-pyridin-2-yl-2H-pyrazol-3-ylamine in the form of a white solid(2.75 g, 5.3%).

¹H NMR (400 MHz, d₆-DMSO):

8.40 (1H, m, H_(pyridine)), 7.93 (1H, m, H_(pyridine)), 7.86 (1H, m,H_(pyridine)), 7.36 (1H, J=2 Hz, H_(pyrazole)), 7.23 (1H, m,H_(pyridine)), 6.78 (2H, S_(broad)), NH₂), 5.42 (1H, J=2 Hz,H_(pyrazole)).

Elemental analysis: (C₈H₈N₄): found: C: 58.30%, H: 4.96%, N: 33.42%.theoretical: C: 59.99%, H: 5.03%, N: 34.98%.

Synthesis of 4-nitroso-2-pyridin-2-yl-2H-pyrazol-3-yl-amine (2):

HCl (37%, 11 μl) was added to a heterogeneous solution of2-pyridin-2-yl-2H-pyrazol-3-ylamine (2.2 g, 13.7 mmol) in absoluteethanol (15 ml). The reaction mixture was subsequently cooled to 0° C.and isopentyl nitrite (2.02 ml, 15 mmol) was slowly added. The reactionmixture became dark. After the isopentyl nitrite had been completelyadded, the reaction mixture was allowed to return to ambienttemperature. After 2.5 h at ambient temperature, the reaction mixturewas cooled to 5° C. and filtered. The solid was washed with absoluteMeOH (10 ml) and was then triturated twice from heptane. The solid wasdried under vacuum at 35° C. to give4-nitroso-2-pyridin-2-yl-2H-pyrazol-3-ylamine (2.1 g, 81%) in the formof a green solid.

¹H NMR (400 MHz, d₆-DMSO): 9.21 (2H, s, NH₂), 8.97 (1H, s,H_(pyrazole)), 8.49 (1H, m, H_(pyridine)), 8.04 (1H, m, H_(pyridine)),7.92 49 (1H, m, H_(pyridine)), 7.40 (1H, m, H_(pyridine)).

¹³C NMR (400 MHz, d₆-DMSO): 152.5, 152.3, 147.2, 143.9, 139.7, 135.0,121.3, 113.0.

Elemental analysis: (C₈H₇N₅O): found: C: 51.19%, H: 3.95%, N: 36.79%, O:8.09%. theoretical: C: 50.79%, H: 3.73%, N: 37.02%, O: 8.46%.

Synthesis of 2-pyridin-2-yl-2H-pyrazole-3,4-diamine hydrochloride (3):

A mixture of 4-nitroso-2-pyridin-2-yl-2H-pyrazol-3-yl-amine (2.0 g, 10.5mmol) in EtOH (130 ml) containing a 10% Pd/C catalyst (Engelhard, 50%moisture, 410 mg) was hydrogenated in an autoclave (250 ml) at 6 bar for3.0 h. The catalyst was filtered off under an inert atmosphere andwashed with EtOH (50 ml), and the filtrate was recovered in an ethanolicsolution (50 ml) comprising hydrochloric acid (37%, 1.3 ml). Theorange-colored solution is evaporated to dryness. The crude product istriturated twice from the minimum amount of EtOH (20 ml) to give thehydrochloride (1.84 eq HCl) of 2-pyridin-2-yl-2H-pyrazole-3,4-diamine(1.5 g, 59%) in the form of a light beige solid.

Elemental analysis: (C₈H₉N₅.1.77HCl; MW=242.28 g/mol) found: C: 39.09%,H: 4.43%, N: 28.21%, Cl: 27.81%. theoretical: C: 40.08%, H: 4.53%, N:29.21%, Cl: 26.17%.

¹H NMR (400 MHz, d₆-DMSO): 10.30 (2H, s, HCl), 8.64 (1H, m,H_(pyridine)), 8.24–8.05 (2H, m, H_(pyridine)), 7.77 (1H, s,H_(pyrazole)), 7.68–7.50 (5H, m, NH₂ and H_(pyridine)).

Examples of Dye Composition in Alkaline Medium

The following composition is prepared: diaminopyrazole base of formula(I) 5 × 10⁻³ mol coupler 5 × 10⁻³ mol oleyl alcohol polyglycerolatedwith 4.0 g 2 mol of glycerol oleyl alcohol polyglycerolated with 5.7 gA.M. 4 mol of glycerol, containing 78% active material (A.M.) oleic acid3.0 g oleylamine containing 2 mol of ethylene 7.0 g oxide, sold underthe trade name Ethomeen O12 by the company Akzo diethylaminopropyllaurylamino succinamate, 3.0 g A.M. sodium salt, at 55% A.M. oleylalcohol 5.0 g oleic acid diethanolamide 12.0 g propylene glycol 3.5 gethyl alcohol 7.0 g dipropylene glycol 0.5 g propylene glycol monomethylether 9.0 g sodium metabisulfite as an aqueous 0.455 g A.M. solutioncontaining 35% A.M. ammonium acetate 0.8 g antioxidant, sequesteringagent qs fragrance, preserving agent qs aqueous ammonia containing 20%NH₃ 100 g pH = 9.5 A.M. means “active material”

The base and the coupler are as defined below.

DYEINGS AT ALKALINE pH Examples Base Coupler 1 2-pyridin-2-yl-m-aminophenol 2H-pyrazole-3,4-diamine 2 2-pyridin-2-yl-6-chloro-2-methyl- 2H-pyrazole-3,4-diamine 5-aminophenol 32-pyridin-2-yl- 2,4-diamino- 2H-pyrazole-3,4-diamine1-(β-hydroxyethyloxy)- benzene dihydrochloride 4 2-pyridin-2-yl-2-methyl-5-aminophenol 2H-pyrazole-3,4-diamine

At the time of use, each dye composition is mixed, weight for weight,with a 20-volumes aqueous hydrogen peroxide solution (6% by weight), thepH of which has been adjusted to about 2.5 with orthophosphoric acid.

The mixture is applied to natural gray hair containing 90% white hairs,at a rate of 5 g per 0.5 g of hair.

After 30 minutes, the hair is rinsed, washed with a standard shampoo,rinsed again and dried.

The color of the locks was evaluated in the L*a*b* system, on white andpermanent-waved hair, using a Minolta CM 2002 spectrophotometer.

In the L*a*b* space, the lightness is indicated by the value L* on ascale from 0 to 100, while the chromatic data is expressed by a* and b*which indicate two color axes, a* the red-green axis and b* theyellow-blue axis.

According to this system, the higher the value of L, the paler and lessintense the color. Conversely, the lower the value of L, the darker ormore intense the color.

White hair Examples L* a* b* Example 1 32.1 21.4 6.18 Example 2 41.824.2 19.0 Example 3 29.2 20.9 5.4 Example 4 43.9 20.4 22.43

The diaminopyrazoles according to the invention thus make it possible toobtain strong and chromatic shades at alkaline pH.

Example of Dyeing Composition in Neutral Medium

The same formulations as above are prepared, replacing the aqueousammonia with citric acid in an amount such that the pH is equal to 7.

DYEING AT NEUTRAL pH Example Base Coupler 5 2-pyridin-2-yl-2H-pyrazole-2-methyl-5-amino- 3,4-diamine phenol

Locks of natural gray hair containing 90% white hairs are dyed with thedye composition 5 above in the same manner as for the dyeing at alkalinepH.

The following shades are obtained:

Natural white hair Example L* a* b* Example 5 42.5 15.8 23.8

At neutral pH, the diaminopyrazoles according to the invention make itpossible to obtain strong shades.

1. A diaminopyrazole compound of formula (I):

in which Ar is a pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl,pyrrolyl, imidazolyl, pyrazolyl, furanyl, thiophenyl, triazolyl,triazinyl, naphthyl, azanaphthyl, diazanaphthyl, triazanaphthyl, ortetraazanaphthyl radical or a physiologically acceptable salt thereof.2. The compound of claim 1, wherein Ar is substituted by at least oneradical chosen from linear or branched C₁ to C₆ alkyl radicals, linearor branched C₁ to C₆ alkoxy radicals, linear or branched C₁ to C₆ mono-or polyaminoalkyl radicals, linear or branched C₁ to C₆ mono- orpolyhydroxyalkyl radicals, amino, hydroxyl, F, Cl, Br, I,trifluoromethyl, CHO, CO₂H, CO₂Me, CO₂Et, CONH₂, CONHR₁, CON(R₁)₂, SO₃H,SO₂NH₂, SO₂Me or piperazinyl radicals, or phenyl radicals optionallysubstituted by at least one radical chosen from linear or branched C₁ toC₆ alkyl radicals, linear or branched C₁ to C₆ alkoxy radicals, linearor branched C₁ to C₆ mono- or polyaminoalkyl radicals, linear orbranched C₁ to C₆ mono- or polyhydroxyalkyl radicals or amino, hydroxyl,F, Cl, Br, I, trifluoromethyl, CHO, CO₂H, CO₂Me, CO₂Et, CONH₂, SO₃H,SO₂NH₂, SO₂N(R₁)₂ or SO₂Me radicals, R₁ being chosen from linear orbranched C₁ to C₆ alkyl radicals, linear or branched C₁ to C₆ mono- orpolyaminoalkyl radicals, linear or branched C₁ to C₆ mono- orpolyhydroxyalkyl radicals, or trifluoromethyl, CHO, CO₂Me, CO₂Et, CONH₂,SO₃H, SO₂NH₂ or SO₂Me radicals, or a physiologically acceptable salt ofany of these.
 3. The compound of claim 1, wherein the Ar radical is aquinolinyl, isoquinolinyl, oxyisoquinolinyl, quinoxalinyl ornaphthyridinyl, acridinyl, pyrazolo[3,4-b]pyridinyl,pyrazolo[3,4-c]pyridazinyl, or thieno[3,2-c]pyridinyl radical.
 4. Thecompound of claim 1, wherein the Ar radical is a pyridinyl radical. 5.The compound of claim 1, further defined as2-pyridin-2-yl-2H-pyrazole-3,4-diamine,2-isoquinolin-1-yl-2H-pyrazole-3,4-diamine,2-(6-methyl-4-trifluoromethylpyridin-2-yl)-2H-pyrazole-3,4-diamine,2-(6-chloro-4-trifluoromethylpyridin-2-yl)-2H-pyrazole-3,4-diamine,2-(5-chloro-3,6-bistrifluoromethylpyridin-2-yl)-2H-pyrazole-3,4-diamine,2-(1,3,4-trimethyl-1H-pyrazolo[3,4-b]pyridin-6-yl)-2H-pyrazole-3,4-diamine,2-(3-aminopyridin-2-yl)-2H-pyrazole-3,4-diamine,2-(5-aminopyridin-2-yl)-2H-pyrazole-3,4-diamine,2-(5,7-bistrifluoromethyl[1,8]naphthyridin-2-yl)-2H-pyrazole-3,4-diamine,2-(2-oxyisoquinolin-3-yl)-2H-pyrazole-3,4-diamine,2-(3-amino-4-methyl-1H-pyrazolo[3,4-b]pyridin-6-yl)-2H-pyrazole-3,4-diamine,2-(6-fluoropyridin-2-yl)-2H-pyrazole-3,4-diamine,2-(4,6-bistrifluoromethylpyridin-2-yl)-2H-pyrazole-3,4-diamine,2-(6-chloropyridin-2-yl)-2H-pyrazole-3,4-diamine,2-(4,5-bistrifluoromethylpyridin-2-yl)-2H-pyrazole-3,4-diamine,2-(5-trifluoromethylpyridin-2-yl)-2H-pyrazole-3,4-diamine,2-(3-methanesulfonyl-4,6-dimethylpyridin-2-yl)-2H-pyrazole-3,4-diamine,2-(4,5-diaminopyrazol-1-yl)pyridine-3,5-diamine,2-(3-amino-5-trifluoromethylpyridin-2-yl)-2H-pyrazole-3,4-diamine,2-(3-trifluoromethylpyridin-2-yl)-2H-pyrazole-3,4-diamine,2-(4-amino-3,5-difluoropyridin-2-yl)-2H-pyrazole-3,4-diamine,2-(4-amino-3,5,6-trifluoropyridin-2-yl)-2H-pyrazole-3,4-diamine,2-thieno[3,2-c]pyridin-4-yl-2H-pyrazole-3,4-diamine,2-pyridin-3-yl-2H-pyrazole-3,4-diamine,2-pyridin-4-yl-2H-pyrazole-3,4-diamine,2-(7-chloroquinolin-4-yl)-2H-pyrazole-3,4-diamine,2-acridin-9-yl-2H-pyrazole-3,4-diamine,2-(3,5-dichloropyridin-4-yl)-2H-pyrazole-3,4-diamine,3,5,6-trichloro-4-(4,5-diaminopyrazol-1-yl)pyridine-2-carboxylic acid,2-(2-bromopyridin-4-yl)-2H-pyrazole-3,4-diamine,2-quinolin-4-yl-2H-pyrazole-3,4-diamine,2-(7-methylquinolin-4-yl)-2H-pyrazole-3,4-diamine,2-(8-trifluoromethylquinolin-4-yl)-2H-pyrazole-3,4-diamine,2-(7-aminoquinolin-4-yl)-2H-pyrazole-3,4-diamine,2-(7-fluoroquinolin-4-yl)-2H-pyrazole-3,4-diamine,2-(7-bromoquinolin-4-yl)-2H-pyrazole-3,4-diamine,2-(7-methoxyquinolin-4-yl)-2H-pyrazole-3,4-diamine,2-(7-ethylquinolin-4-yl)-2H-pyrazole-3,4-diamine,2-(7-methylquinolin-4-yl)-2H-pyrazole-3,4-diamine,2-(2,6-dimethylquinolin-4-yl)-2H-pyrazole-3,4-diamine,2-(8-isopropyl-2-methylquinolin-4-yl)-2H-pyrazole-3,4-diamine,2-(2,6,8-trimethylquinolin-4-yl)-2H-pyrazole-3,4-diamine,2-(5-chloro-8-methoxy-2-methylquinolin-4-yl)-2H-pyrazole-3,4-diamine,2-(3-methanesulfonylpyridin-4-yl)-2H-pyrazole-3,4-diamine,2-pyrazin-2-yl-2H-pyrazole-3,4-diamine,2-quinoxalin-2-yl-2H-pyrazole-3,4-diamine,2-(3,7-dichloroquinoxalin-2-yl)-2H-pyrazole-3,4-diamine,2-(5-chloro-3,6-diphenylpyrazin-2-yl)-2H-pyrazole-3,4-diamine,2-(3-trifluoromethylquinoxalin-2-yl)-2H-pyrazole-3,4-diamine,2′H-[1,3′]bipyrazolyl-4,5-diamine,2′,5′-dimethyl-2′H-[1,3′]bipyrazolyl-4,5,4′-triamine,2-(4,5-diphenyl-1H-pyrazolo[3,4-c]pyridazin-3-yl)-2H-pyrazole-3,4-diamine,ethyl ester of 4,5-diamino-5′-methyl-2′H-[1,3′]bipyrazolyl-4′-carboxylicacid, 1′H-[1,4′]bipyrazolyl-4,5-diamine,2-pyrimidin-4-yl-2H-pyrazole-3,4-diamine,2-(2-aminopyrimidin-4-yl)-2H-pyrazole-3,4-diamine,2-(2,6-dichloropyrimidin-4-yl)-2H-pyrazole-3,4-diamine,2-pyrimidin-5-yl-2H-pyrazole-3,4-diamine,2-(2,4,6-trichloropyrimidin-5-yl)-2H-pyrazole-3,4-diamine,2-(2-piperazin-1-yl-pyrimidin-5-yl)-2H-pyrazole-3,4-diamine,2-furan-2-yl-2H-pyrazole-3,4-diamine,5-(4,5-diaminopyrazol-1-yl)-furan-2-carbaldehyde,2-(4-bromofuran-2-yl)-2H-pyrazole-3,4-diamine,2-(4-phenylfuran-2-yl)-2H-pyrazole-3,4-diamine,[5-(4,5-diaminopyrazol-1-yl)-furan-2-yl]methanol,5-(4,5-diaminopyrazol-1-yl)-furan-3-carboxylic acid,3-(4,5-diaminopyrazol-1-yl)furan,[5-(4,5-diaminopyrazol-1-yl)-furan-3-yl]methanol,3-(4,5-diaminopyrazol-1-yl)-5H-furan-2-one,2-thiophen-2-yl-2H-pyrazole-3,4-diamine,5-(4,5-diaminopyrazol-1-yl)thiophene-2-carbaldehyde,2-(4-bromothiophen-2-yl)-2H-pyrazole-3,4-diamine,2-(4-isopropylthiophen-2-yl)-2H-pyrazole-3,4-diamine,2-(5-aminomethylthiophen-2-yl)-2H-pyrazole-3,4-diamine,5-(4,5-diaminopyrazol-1-yl)thiophene-3-carboxylic acid,2-thiophen-3-yl-2H-pyrazole-3,4-diamine,[5-(4,5-diaminopyrazol-1-yl)thiophen-3-yl]methanol,2-(3H-[1,2,3]triazol-4-yl)-2H-pyrazole-3,4-diamine,2-(2H-[1,2,4]triazol-3-yl)-2H-pyrazole-3,4-diamine,2-(2-phenyl-2H-[1,2,4]triazol-3-yl)-2H-pyrazole-3,4-diamine,2-[1,3,5]triazin-2-yl-2H-pyrazole-3,4-diamine,2-(4,6-dichloro[1,3,5]triazin-2-yl)-2H-pyrazole-3,4-diamine,2-(4,6-difluoro[1,3,5]triazin-2-yl)-2H-pyrazole-3,4-diamine,2-(1H-pyrrol-3-yl)-2H-pyrazole-3,4-diamine,2-(1H-pyrrol-2-yl)-2H-pyrazole-3,4-diamine,2-(1H-imidazol-2-yl)-2H-pyrazole-3,4-diamine,2-(1H-imidazol-4-yl)-2H-pyrazole-3,4-diamine,2-pyridazin-3-yl-2H-pyrazole-3,4-diamine,2-pyridazin-4-yl-2H-pyrazole-3,4-diamine or a physiologically acceptableacid salt of any of these.
 6. The compound of claim 1, further definedas 2-pyridin-2-yl-2H-pyrazole-3,4-diamine,2-isoquinolin-1-yl-2H-pyrazole-3,4-diamine,2-thieno[3,2-c]pyridin-4-yl-2H-pyrazole-3,4-diamine,2-pyridin-3-yl-2H-pyrazole-3,4-diamine,2-quinolin-4-yl-2H-pyrazole-3,4-diamine,2-pyrazin-2-yl-2H-pyrazole-3,4-diamine,2-quinoxalin-2-yl-2H-pyrazole-3,4-diamine,2′H-[1,3′]bipyrazolyl-4,5-diamine, 1′H-[1,4′]bipyrazolyl-4,5-diamine,2-pyrimidin-4-yl-2H-pyrazole-3,4-diamine,2-pyrimidin-5-yl-2H-pyrazole-3,4-diamine,2-furan-2-yl-2H-pyrazole-3,4-diamine,2-(4-bromofuran-2-yl)-2H-pyrazole-3,4-diamine,3-(4,5-diaminopyrazol-1-yl)furan,5-(4,5-diaminopyrazol-1-yl)furan-3-carboxylic acid,3-(4,5-diaminopyrazol-1-yl)-5H-furan-2-one,2-thiophen-2-yl-2H-pyrazole-3,4-diamine,2-thiophen-3-yl-2H-pyrazole-3,4-diamine,2-(3H-[1,2,3]triazol-4-yl)-2H-pyrazole-3,4-diamine,2-(2H-[1,2,4]triazol-3-yl)-2H-pyrazole-3,4-diamine,2-[1,3,5]triazin-2-yl-2H-pyrazole-3,4-diamine,2-(1H-pyrrol-3-yl)-2H-pyrazole-3,4-diamine,2-(1H-pyrrol-2-yl)-2H-pyrazole-3,4-diamine,2-(1H-imidazol-2-yl)-2H-pyrazole-3,4-diamine,2-(1H-imidazol-4-yl)-2H-pyrazole-3,4-diamine,2-pyridazin-3-yl-2H-pyrazole-3,4-diamine,2-pyridazin-4-yl-2H-pyrazole-3,4-diamine or a physiologically acceptableacid salt of any of these.
 7. The compound of claim 1, further definedas a physiologically acceptable hydrochloride, hybrobromide, sulfate,tartrate, lactate, or acetate acid salt.
 8. A composition for theoxidation dyeing of keratin fibers comprising at least onediaminopyrazole of formula (I):

in which Ar is a 5- or 6-membered heteroaromatic radical which can becondensed with one or more aromatic or heteroaromatic rings, eachcomprising 5 or 6 ring members, or a physiologically acceptable saltthereof, in a medium suitable for dyeing.
 9. The composition of claim 8,further defined as comprising from 0.001% to 10% by weight of at leastone diaminopyrazole of formula (I) or salt thereof.
 10. The compositionof claim 8, wherein the medium that is suitable for dyeing compriseswater or of a mixture of water and at least one organic solvent furtherdefined as a C₁–C₄ lower alkanol, polyol, polyol ether, or aromaticalcohol, or mixtures thereof.
 11. The composition of claim 8, furtherdefined as having a pH of between 3 and
 12. 12. The composition of claim8, comprising at least one additional oxidation base further defined asa para-phenylenediamine, bis(phenyl)alkylenediamine, para-aminophenol,ortho-aminophenol, or heterocyclic base other than the diaminopyrazoleof formula (I), or an addition salt of one of these with an acid. 13.The composition of claim 12, wherein the additional oxidation basecomprises from 0.0005% to 12% by weight relative to the total weight ofthe dye composition.
 14. The composition of claim 8, further defined ascomprising at least one direct dye.
 15. The composition of claim 8,further defined as comprising at least one coupler.
 16. The compositionof claim 15, wherein the coupler is a meta-phenylenediamine,meta-aminophenol, meta-diphenol, monohydroxylated naphthalenederivative, polyhydroxylated naphthalene derivative, or heterocycliccoupler, or an addition salt of one of these with an acid.
 17. Thecomposition of claim 15, wherein the coupler represents from 0.0001% to10% by weight relative to the total weight of the dye composition. 18.The composition of claim 8, further defined as comprising at least onedirect dye and at least one coupler.
 19. A process for dyeing keratinfibers, comprising applying to the fibers a composition comprising, asan oxidation base, at least one diaminopyrazole of formula (I):

in which Ar is a 5- or 6-membered heteroaromatic radical which can becondensed with one or more aromatic or heteroaromatic rings, eachcomprising 5 or 6 ring members, or a physiologically acceptable saltthereof, in a medium suitable for dying, for a time that is sufficientto develop the desired coloration, either in air or using an oxidizingagent.
 20. The process of claim 19, wherein the keratin fibers arefurther defined as human hair.
 21. The process of claim 19, furthercomprising applying an oxidation catalyst to the fibers.
 22. The processof claim 19, wherein no oxidizing agent is applied and coloration isrevealed by contact with atmospheric oxygen.
 23. The process of claim19, further comprising an application of an oxidizing agent to thefibers.
 24. The process of claim 23, wherein the oxidizing agent isadded to the dye composition prior to application of the dye compositionto the fibers.
 25. The process of claim 23, wherein the oxidizing agentis comprised in an oxidizing composition that is applied to the fiberssimultaneously or sequentially with regard to the dyeing composition.26. The process of claim 23, wherein the oxidizing agent is hydrogenperoxide, urea peroxide, an alkali metal bromate, or a persalt.
 27. Akit comprising: a first compartment containing a composition comprisinga diaminopyrazole of formula (I):

 in which Ar is a 5- or 6-membered heteroaromatic radical which can becondensed with one or more aromatic or heteroaromatic rings, eachcomprising 5 or 6 ring members, or a physiologically acceptable saltthereof, in a medium suitable for dying; and a second compartmentcontaining an oxidizing composition.
 28. A composition for the oxidationdyeing of keratin fibers comprising from 0.001% to 10% by weight of atleast one diaminopyrazole of formula (I):

in which Ar is a 5- or 6-membered heteroaromatic radical which can becondensed with one or more aromatic or heteroaromatic rings, eachcomprising 5 or 6 ring members, or a physiologically acceptable saltthereof, in a medium suitable for dyeing.
 29. A process for dyeing humanhair, comprising applying to the hair a composition comprising, as anoxidation base, at least one diaminopyrazole of formula (I):

in which Ar is a 5- or 6-membered heteroaromatic radical which can becondensed with one or more aromatic or heteroaromatic rings, eachcomprising 5 or 6 ring members, or a physiologically acceptable saltthereof, in a medium suitable for dying, for a time that is sufficientto develop the desired coloration, either in air or using an oxidizingagent.